The U.S. 9th Circuit Court of Appeals heard arguments April 12 in the legal battle over the matching funds provision of Arizona’s Clean Elections system, clearing the way for a high-stakes ruling that could define how the state’s top political races play out in the coming weeks.

The system that allows Arizona residents to use government money to campaign for political office is teetering after a federal judge ruled earlier this year that a major component of the scheme is unconstitutional. Many powerful special interest groups, nonetheless, are hoping to deliver the knockout blow at the ballot box this fall, rather than wait for it to collapse on its own.